1. Field of the Invention
The present invention relates to an output control system for an engine with an exhaust control device, and more particularly to an output control system for an engine equipped with an exhaust control function which controls an exhaust pulse by providing means such as a valve for changing an exhaust gas passage cross-sectional area midway in an engine exhaust air system.
2. Description of the Background Art
In Japanese Patent Laid-Open No. 1-313621 or 2002-138828, there has been disclosed a technique for improving engine output by reducing resistance within an exhaust passage in a high speed area of an engine and utilizing a pulsation effect, or arranging an exhaust control valve for making the exhaust gas cross-sectional area variable within the exhaust passage in order to improve the startability for dynamically changing its throttle angle in accordance with control parameters such as a vehicle speed and an engine speed.
Assuming that the above-described exhaust control valve is functioning normally, fundamental ignition timing and fundamental injection quantity of fuel in a vehicle mounted with the above-described exhaust control valve are determined with a throttle angle, engine speed, vehicle speed or the like as parameters. Thus, actual ignition timing and fuel injection quantity are determined by multiplying these fundamental ignition timing and fundamental injection quantity of fuel by various correction factors. Therefore, since when the exhaust control valve is functioning abnormally for some reason or other, the fundamental ignition timing or the fundamental injection quantity deviates from the optimum value, there is a possibility of causing problems such as deteriorated engine performance and lowered fuel economy.
It is an object of the present invention to solve the above-described problems of the conventional technique, and to provide an engine exhaust control device capable of obtaining sufficient traveling performance even when the exhaust control valve is functioning abnormally.